Pneumatic tire having sidewalls of unequal length

ABSTRACT

A pneumatic tire having sidewalls of unequal length and a carcass constructed to conform when uninflated to equilibrium cross-sectional shape, the shorter sidewall terminating radially inwardly by that point at which the equilibrium shape of the sidewall becomes perpendicular relative to the axis of rotation of the tire.

llmted States Patent 1191 Gough et al. Oct. 22, 1974 [54] PNEUMATIC TIRE HAVING SIDEWALLS [56] References Cited OF UNEQUAL LENGTH UNITED STATES PATENTS [75] Inventors: Vernon E. Gough, Croyde; Roy E. S. 2,028,702 1/1936 Hale l52/DIG. 6

galllerhsutton Coldfield, both of FOREIGN PATENTS OR APPLICATIONS an 1,192,380 4 1959 France 1. 152/352 [73] Assignee: The Dunlop Company Limited,

London, England Primary ExaminerM. Henson Wood, Jr. Assistant Examiner-Richard A. Bertsch [22] Flled" Sept 1971 Attorney, Agent, or FirmStevens, Davis, Miller & [21] Appl. No.: 180,182 Mosher Related U.S. Application Data [57] ABSTRACT [63] Continuation of Ser. No. 858,957, Sept. 18, 1969, A

abandoned I pneumat1c tIre havmg sIdewalls of unequal length I and a carcass constructed to conform when unmflated U s 6 t0 equilibrium Cross-Sectional Shapfi, the Shorter Side" 52/361 wall terminating radially inwardly by, that pointv at [5]] 1m Cl j 1360c 5/00 which the equilibrium shape of the sidewall becomes [58] Fie'ld 352 R perpendicular relative to the axis of rotation of the 5 Claims, 2 Drawing Figures PNEUMATIC TIRE HAVING SIDEWALLS OF UNEQUAL LENGTH This is a continuation of application Ser. No. 858,957, filed Sept. 18, 1969, now abandoned.

This invention relates to tubeless or tubed pneumatic tires.

It is usual that one shoulder of a tire tread becomes more worn than the other. This unevenness of wear is caused by rolling of the vehicle during cornering, the axially outermost sidewall of the tire, located on the sidewall of the tire located on the side of a vehicle outermost of the curve, carrying a larger load than the other sidewall.

It is an object of thepresent invention to provide'a tire in which the unequal loading is accounted for.

In the present specificationthe words equilibrium cross-sectional shape", wherever referredto, mean that shape of a tire which is obtained when a thin-wall tire carcass is inflated under higher than normal inflation pressure, the cord path of the uninflated tire carcass conforming to'this shape, the-equilibrium shapebeing unchanged upon inflation.

According to theinventionthere'is provided a pneumatic tire having sidewalls of unequal length and a carcass constructed to conform when uninflated to equilibrium cross-sectional shape as herein defined the shorter sidewall terminating radially inwardly of that point at which the'equilibrium shape of the sidewall becomes perpendicular when viewed in cross-section to the axis of rotation of the tire.

The pneumatic tire may be tubed or tubeless.

The sidewalls may be constructed to be similar in all respects apart from their length or, alternatively, one sidewall, preferably the longer, may-be reinforced additionally by ply extension or separate reinforcing layers compared with the other for its whole length, in some instances the reinforcement extending from a sidewall over the crown of the tire to form a breaker or addi tional breaker reinforcement. Alternatively, the reinforcement may be confined to that portion of the Alternatively, one sidewall can be reinforced from one bead to the crown region with a carcass ply of radial cords and the other sidewall with a carcass ply or plies of bias cords extending from its bead to the crown region in which region the carcass plies may overlap. In this alternative, the sidewalls provided with a carcass ply of radial cords will have a shape corresponding to that of the sidewall of an equilibrium-shaped symmetrical section radial ply tire, and the sidewall provided with a carcass ply of cross-ply cords will have a shape corresponding to that particular equilibrium shape of the sidewall of a symmetrical section cross-ply tire different from the shape of the radial ply sidewall. Thus the equilibrium shape of each sidewall is appropriate to its cord-angle construction. The shorter or alternatively The crown region of the tire may be reinforced with low angle breaker layers e.g. 10 to 25 to form a belted tire.

The difference in length between one sidewall and 5 the other should not be less than one quarter of an inch the longer sidewall may be the region of the tire having the radial cord ply.

but can be substantially more; it should not, however, terminate beyond (radially outwardly of) that point at which the equilibrium shape of the sidewall becomes perpendicular (when viewed in cross-section) with the axis of rotation of the tire. In the case of car tires the preferred difference in bead base diameter between the two sidewalls is one inch where the bases of the beads are at an identical taper angle (e.g. both'at aconventional 5 to 15 taper), the preferred corresponding difference, where the taper angle is 5 in one bead and 15 on the other, being either one half an inch or 1' /2 inches. It can be said that the range of difference in bead-base diameter of the sidewalls normally lies between 5 and 12 per cent of the larger diameter bead-base. I

The invention also includes within its scope a tire and wheel, the tire being inflated upon the wheel and, on account of its equilibrium cross-sectional shape, being substantially symmetrically deflected radially under vertical staticload despite the unequal sidewall length and not subject to asymmetric sideways deflection or asymmetric tilting.

The invention further includes a vehicle having fitted "thereto a wheel and tire in accordance with a previously defined aspect of the invention, the wheel and tire being fitted with the longer sidewall disposedaxi- -wmanxins.d via vhsreini i FIG. 1 illustrates a diagrammatic axial crosssectional view of a pneumatic tire fitted to a rim.

FIG. 2 illustrates a diagrammatic axial crosssectional view of the tire illustrated in F IG. 1 during use thereof whentravelling along the outside of a curved path.

A motor car tire I is constructed from a single textile ply of radial cords to form a carcass reinforcemen't Z, the ply being wrapped around annular bead wires 3a and 3b, in the usual manner, one bead wire 3a having a larger diameter than the other bead wire 3b, so that one sidewall 2a of the carcass will terminate short of the other 2b, i.e., it will have a larger diameter at the bead base. The profile of the carcass 2 is such that the shorter carcass sidewall 2a is a mirror image shape of the other sidewall 2b for that length of it which corresponds.

The carcass 2 is provided with a breaker assembly 4 formed of two layers 5 and 6 of steel cords disposed at about 20 to the mid-circumferential plane X-X of the tire tread, the assembly being moulded in a conventional manner, to the equilibrium cross-sectional shape as defined herein, the bead seats 7a and 7b being moulded to have a taper of 5 and 15 respectively. The difference in diameter of one bead seat 7a with respect to the other bead seat 7b is one inch the bead seat 7a being of largest diameter and a wheel10 is provided having a rim 9 provided with appropriate bead seats and distances between flanges such that the tire mounted on the wheel, and inflated to normal pressure has no tendency for the cross-sectional shape of the tire to change when compared with its shape despite the unequal length, and when the tire is subjected to vertical static load, no asymmetric sideways deflection is set up or asymmetric tilting of the tread. The tire and wheel are fitted to a vehicle in a manner such that the longer sidewall 12b is disposed axially outwardly of the longitudinal axis of the vehicle.

During use of such a tire fitted to a wheel 10 when negotiating a bend or corner as illustrated in FIG. 2, it will be appreciated that by reason of the rolling of the vehicle (not shown) to which the wheel 10 is attached the axially outermost sidewall 12b of the tire located on the side of the vehicle outermost of the curve carries a larger load than the other sidewall 12a. The greater length of said axially outermost sidewall 12b allows the unequal loading to be accounted for.

In addition it will be seen from FIG. 2 that the provision of a rim 9 having a portion thereof 90 of relatively large diameter permits a brake device 11 to be accommodated in the wheel hub, without difficulty.

Having now described our invention, what we claim 1. A pneumatic tire having sidewalls of unequal length and a carcass having at least one ply of reinforcing cords, the cross-sectional shape of the carcass conforming, over the range of inflation pressure from uninflated to fully inflated, to the equilibrium crosssectional shape for a carcass of corresponding width and cord angle, each sidewall terminating in a bead at a position radially inwardly of the point at which the equilibrium shape of the sidewall becomes perpendicular, when viewed in cross-section, to the axis of rotation of the tire.

2. A pneumatic tire according to claim 1 wherein the difference in bead base diameter of the sidewalls lies within the range 5 to 12% of the larger diameter bead base.

3. A pneumatic tire according to claim 1 wherein the bases of the bead are provided with different taper angles.

4. A pneumatic tire according to claim 1 and a wheel, the tire being inflated upon the wheel to conform to equilibrium cross-sectional shape.

5. A pneumatic tire having sidewalls of unequal length and a carcass having at least one ply of reinforcing cords, the cross-sectional shape of the carcass conforming, over the range of inflation pressure from uninflated to fully inflated, to the equilibrium crosssectional shape for a carcass of corresponding width and cord angle, each sidewall containing cords of the same angle and terminating in a bead at a position radially inwardly of the point at which the equilibrium shape of the sidewall becomes perpendicular, when viewed in cross-section, to the axis of rotation of the tire, the shorter sidewall being a mirror image of the corresponding length of the longer sidewall in crosssectional shape. 

1. A pneumatic tire having sidewalls of unequal length and a carcass having at least one ply of reinforcing cords, the crosssectional shape of the carcass conforming, over the range of inflation pressure from uninflated to fully inflated, to the equilibrium cross-sectional shape for a carcass of corresponding width and cord angle, each sidewall terminating in a bead at a position radially inwardly of the point at which the equilibrium shape of the sidewall becomes perpendicular, when viewed in cross-section, to the axis of rotation of the tire.
 2. A pneumatic tire according to claim 1 wherein the difference in bead base diameter of the sidewalls lies within the range 5 to 12% of the larger diameter bead base.
 3. A pneumatic tire according to claim 1 wherein the bases of the bead are provided with different taper angles.
 4. A pneumatic tire according to claim 1 and a wheel, the tire being inflated upon the wheel to conform to equilibrium cross-sectional shape.
 5. A pneumatic tire having sidewalls of unequal length and a carcass having at least one ply of reinforcing cords, the cross-sectional shape of the carcass conforming, over the range of inflation pressure from uninflated to fully inflated, to the equilibrium cross-sectional shape for a carcass of corresponding width and cord angle, each sidewall containing cords of the same angle and terminating in a bead at a position radially inwardly of the point at which the equilibrium shape of the sidewall becomes perpendicular, when viewed in cross-section, to the axis of rotation of the tire, the shorter sidewall being a mirror image of the corresponding length of the longer sidewall in cross-sectional shape. 